How long do you have to be in Britain before claiming the right to call it yours? Is it about years of residence? Or land? Or lineage? Perhaps a piece of paper from the government? Once it's yours, can it be taken back?

I have to fill out a form that asks about my parents. Are they British nationals? If so, when did they become so? What's the number on the certificate?

These are not unreasonable questions in themselves, but they reminded me with a jolt that the status of me and mine wasn't always assured. My parents – having journeyed from the colony that was Jamaica – were subsequently required by the Thatcher government to find money they could only just afford to secure their position. I recall my late mother being aggrieved and I learned, amid her mutterings, a new word: "patrial" – there was debate about whether she had additional rights stemming from Scottish ancestors. My parents paid the money, for themselves and my elder siblings who were born in the Caribbean, but the whole thing was a shock. After 30 years as Commonwealth citizens, it suddenly transpired that their claim to call London home wasn't quite as it seemed.

A book is doing the rounds, Exodus: Immigration and Multiculturalism in the 21st Century by Paul Collier, the former World Bank economist. It says a bunch of things: that too much diversity loosens the ties that bind societies and that too much migration impoverishes source countries by robbing them of their best people. Some people, mainly on the right, love it. Others pretty much hate it because it seems a gloomy sort of manifesto and they think the analysis questionable. But one line stood out in the book and in the Daily Mail's love-bomb coverage. "The 2011 census revealed that the indigenous British had become a minority in their own capital."

"Indigenous" is interesting in this context. There is no such census category and Britons through birth or citizenship are still the majority in London. So it's white British. Then there is "their own capital". What does that mean, other than London has been wrested from them? I don't think it works like that. I've 50 years invested and other non-white people with more years on the clock might see me as a newbie. This Britain, don't we own it too?